In the manufacturing of a product, the product is usually processed at many work stations or process machines. For example, to complete the fabrication of semiconductor wafers, various processing steps of deposition, cleaning, ion implantation, etching and passivation may be carried out before the semiconductor wafers are packaged for shipment.
In the vast majority of the processing steps, a special environment of either a high vacuum, low vacuum, gas plasma or other chemical environment is provided for the semiconductor wafers in the work stations or process machines. For instance, in a sputter process machine, a high vacuum environment is provided to surround the semiconductor wafer. Metal particles sputtered from a metal target can therefore travel toward and be deposited on the exposed surface of the semiconductor wafer. In other process machines, such as in a plasma enhanced chemical vapor deposition chamber, the plasma cloud of a reactant gas is formed over the semiconductor wafer positioned in a process chamber such that deposition of a chemical substance can occur on the semiconductor wafer.
In the work stations or process machines, the handling of the semiconductor wafer between locations must be conducted carefully to avoid damage to the semiconductor wafer. To accomplish this purpose, the handling of the semiconductor wafer is conducted automatically by a wafer transfer mechanism.
Therefore, accurate positioning of the wafer transfer mechanism in the work stations or process machines is an important aspect of the fabrication process.